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Acheiropodia, also known as Horn Kolb syndrome,[1] is a genetic condition that affects limb development, resulting in shortened arms and legs and absent hands and feet on both sides of the body at birth.[2] Specifically, individuals are born missing the epiphysis typically found at the end of the humerus bone of the upper arm, the diaphysis which makes up the long section of the tibia bone of the shin, the radius and ulna bones which make up the lower arm, the fibula bone of the shin, and all hand and foot bones.[2] It was first discovered and is prevalent almost exclusively in Brazil.[3]
| Acheiropodia | |
|---|---|
| Other names | Horn-Kolb syndrome, acheiropody and aleijadinhos (Brazilian type) |
 | |
| Acheiropodia has an autosomal recessive pattern of inheritance | |
| Specialty | Medical genetics  |
Signs and symptoms
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Genetics
editAcheiropodia results from a change in the DNA sequence of the C7rof2 gene.[4] When this altered DNA is transcribed to RNA, the resulting RNA transcript is processed differently from unaltered RNA. A segment of the processed RNA transcript called exon 4, which codes for a segment of the protein, is missing, causing the process of converting the transcript into a protein to stop too early.[4] This leads to a shorter, non-functional protein.
The C7rof2 gene is the human equivalent of the mouse gene LMBR1, which encodes an essential protein for limb development.[4] When there is no functional protein present, limb development does not occur correctly, and individuals are born with acheiropodia.[4] However, all individuals have two sets of chromosomes and thus two copies of the C7orf2 gene. The non-functional protein resulting from one altered gene does not interfere with the functional copy of the protein, so acheiropodia only occurs in those who have this rare change in both copies of C7orf2.[5] This makes it an autosomal-recessive condition, meaning that individuals will only be affected by acheiropodia if both parents carry one copy of the altered gene without experiencing symptoms, resulting in the inheritance of one rare gene copy from each parent.[5]
The C7rof2 DNA sequence is very stable and changes occur rarely, partly explaining the rarity of this condition.[5] Since the rare gene copy is unlikely to be found in parents from two unrelated families, acheiropodia is often caused by consanguineous marriages in which genetically related individuals have children together.[4]
Diagnosis
editThe rarity and subsequent lack of information on acheiropodia makes prenatal diagnosis difficult. Diagnosis depends on prenatal ultrasound screening, with a failure to visualize bones at the ends of fetal limbs.[1] Due to variable expressivity of the C7rof2 gene, acheiropodia presents differently among affected individuals, adding to the difficulty of diagnosis.[6] Fingers are sometimes present, and a small bone at the tip of the shortened limb (the Bohomoletz bone) may or may not be present.[6]
Acheiropodia has been diagnosed at as early as 16 weeks post-conception,[7] although research on similar conditions suggests it may be diagnosed even earlier.[8] If ultrasound screening indicates possible acheiropodia, further (more invasive) testing may be performed,[9] including genetic analysis of either an amniotic fluid sample or placenta (chorionic villus) sample to confirm diagnosis.[9][10] In the case of fetal death or termination, autopsy findings may conclude in a diagnosis.[9]
Treatment
editEven with early prenatal diagnosis, due to its genetic basis acheiropodia cannot currently be prevented or cured. However, once a child is born with acheiropodia, prosthetics could improve their quality of life.[11] Surgery may be considered on a case-by-case basis to optimize prosthetic fitting.[11] Prosthetic fitting should occur before 2 years of age to minimize the risk of rejection.[11] Ideally, fitting should begin around the 6-9 month mark, when healthy infants typically begin using their hands and feet to stand and handle objects.[11] Even without prosthetics, many children with limb loss learn to functionally use their residual limbs.[12] A multidisciplinary approach may best treat the medical, psychological, and developmental challenges that may occur in infants missing all four limbs.[13]
References
edit- ^ a b Temur, Ismail; Ulker, Kahraman; Volkan, Islim; Karaca, Mehmet; Ersoz, Mustafa; Gul, Abdulaziz; Adiguzel, Esat (2012). "The first case of Horn Kolb Syndrome in Turkey, diagnosed prenatally at the 23rd week of a pregnancy: A very rare and unusual case far from the original geography". American Journal of Case Reports. 13: 106–108. doi:10.12659/ajcr.883025. ISSN 1941-5923. PMC 3615972. PMID 23569502.
- ^ a b Freire-Maia, A.; Freire-Maia, N.; Morton, N. E.; Azevêdo, E. S.; Quelce-Salgado, A. (1975). "Genetics of acheiropodia (the handless and footless families of Brazil). VI. Formal genetic analysis". American Journal of Human Genetics. 27 (4): 521–527. ISSN 0002-9297. PMC 1762812. PMID 1155460.
- ^ Freire-Maia, Ademar; Opitz, John M. (1981). "Historical note: The extraordinary handless and footless families of Brazil – 50 years of acheiropodia". American Journal of Medical Genetics. 9 (1): 31–41. doi:10.1002/ajmg.1320090108. ISSN 0148-7299. PMID 7018242.
- ^ a b c d e Ianakiev, P.; van Baren MJ, null; Daly, M. J.; Toledo, S. P.; Cavalcanti, M. G.; Neto, J. C.; Silveira, E. L.; Freire-Maia, A.; Heutink, P.; Kilpatrick, M. W.; Tsipouras, P. (2001). "Acheiropodia is caused by a genomic deletion in C7orf2, the human orthologue of the Lmbr1 gene". American Journal of Human Genetics. 68 (1): 38–45. doi:10.1086/316955. ISSN 0002-9297. PMC 1234933. PMID 11090342.
- ^ a b c Freire-Maia, A.; Li, W. H.; Maruyama, T. (1975). "Genetics of acheiropodia (the handless and footless families of Brazil). VII. Population dynamics". American Journal of Human Genetics. 27 (5): 665–675. ISSN 0002-9297. PMC 1762833. PMID 1163539.
- ^ a b Grimaldi, Angela; Masiero, D.; Richieri-Costa, A.; Freire-Maia, A.; Opitz, J. M. (1983). "Variable expressivity of the acheiropodia gene". American Journal of Medical Genetics. 16 (4): 631–634. doi:10.1002/ajmg.1320160420. ISSN 0148-7299. PMID 6660253.
- ^ Ülker, Kahraman; Karasu, Yetkin; Bozkurt, Murat; Gençdal, Servet; Bozkurt, Duygu Kara; Şahin, Levent (2015). "The second case of Horn Kolb Syndrome in the same woman in Turkey, diagnosed prenatally at 16 weeks of pregnancy". Proceedings in Obstetrics and Gynecology. 5 (1): 1–6. doi:10.17077/2154-4751.1282. ISSN 2154-4751.
- ^ Sharony, Reuven; Browne, Charlie; Lachman, Ralph S.; Rimoin, David L. (1993-09-01). "Prenatal diagnosis of the skeletal dysplasias". American Journal of Obstetrics and Gynecology. 169 (3): 668–675. doi:10.1016/0002-9378(93)90641-U. ISSN 0002-9378. PMID 8372878.
- ^ a b c Rajala, Katri; Kasanen, Ellamaija; Toiviainen-Salo, Sanna; Valta, Helena; Mäkitie, Outi; Stefanovic, Vedran; Tanner, Laura (2022). "Genetic spectrum of prenatally diagnosed skeletal dysplasias in a Finnish patient cohort". Prenatal Diagnosis. 42 (12): 1525–1537. doi:10.1002/pd.6186. ISSN 0197-3851. PMC 9796183. PMID 35611473.
- ^ Brambati, Bruno; Tului, Lucia (2005). "Chorionic villus sampling and amniocentesis". Current Opinion in Obstetrics and Gynecology. 17 (2): 197–201. doi:10.1097/01.gco.0000162191.22091.e9. ISSN 1040-872X. PMID 15758614. S2CID 25539327.
- ^ a b c d Mano, Hiroshi; Fujiwara, Sayaka; Takamura, Kazuyuki; Kitoh, Hiroshi; Takayama, Shinichiro; Ogata, Tsutomu; Haga, Nobuhiko (2021-07-01). "Treatment approaches for congenital transverse limb deficiency: Data analysis from an epidemiological national survey in Japan". Journal of Orthopaedic Science. 26 (4): 650–654. doi:10.1016/j.jos.2020.05.008. ISSN 0949-2658. PMID 32600906. S2CID 220268893.
- ^ Yigiter, K.; Ulger, O.; Sener, G.; Akdogan, S.; Erbahçeci, F.; Bayar, K. (2005). "Demography and function of children with limb loss". Prosthetics and Orthotics International. 29 (2): 131–138. doi:10.1080/03093640500199703. ISSN 0309-3646. PMID 16281722. S2CID 42037061.
- ^ Lowe, Kevin G.; Boyce, Joanne M. (2004). "Rehabilitation of a child with meningococcal septicemia and quadrilateral limb loss: a case report". Archives of Physical Medicine and Rehabilitation. 85 (8): 1354–1357. doi:10.1016/j.apmr.2003.09.030. ISSN 0003-9993. PMID 15295765.